package net.borderwars.jedit;

/*
 * TextUtilities.java - Utility functions used by the text area classes
 * Copyright (C) 1999 Slava Pestov
 *
 * You may use and modify this package for any purpose. Redistribution is
 * permitted, in both source and binary form, provided that this notice
 * remains intact in all source distributions of this package.
 */

import javax.swing.text.BadLocationException;
import javax.swing.text.Document;

/**
 * Class with several utility functions used by the text area component.
 *
 * @author Slava Pestov
 * @version $Id: TextUtilities.java,v 1.4 1999/12/13 03:40:30 sp Exp $
 */
public class TextUtilities {
    /**
     * Returns the offset of the bracket matching the one at the
     * specified offset of the document, or -1 if the bracket is
     * unmatched (or if the character is not a bracket).
     *
     * @param doc    The document
     * @param offset The offset
     * @throws BadLocationException If an out-of-bounds access
     *                              was attempted on the document text
     */
    public static int findMatchingBracket (Document doc, int offset)
            throws BadLocationException {
        if (doc.getLength () == 0)
            return -1;
        char c = doc.getText (offset, 1).charAt (0);
        char cprime; // c` - corresponding character
        boolean direction; // true = back, false = forward

        switch (c) {
            case'(':
                cprime = ')';
                direction = false;
                break;
            case')':
                cprime = '(';
                direction = true;
                break;
            case'[':
                cprime = ']';
                direction = false;
                break;
            case']':
                cprime = '[';
                direction = true;
                break;
            case'{':
                cprime = '}';
                direction = false;
                break;
            case'}':
                cprime = '{';
                direction = true;
                break;
            default:
                return -1;
        }

        int count;

        // How to merge these two cases is left as an exercise
        // for the reader.

        // Go back or forward
        if (direction) {
            // Count is 1 initially because we have already
            // `found' one closing bracket
            count = 1;

            // Get text[0,offset-1];
            String text = doc.getText (0, offset);

            // Scan backwards
            for (int i = offset - 1; i >= 0; i--) {
                // If text[i] == c, we have found another
                // closing bracket, therefore we will need
                // two opening brackets to complete the
                // match.
                char x = text.charAt (i);
                if (x == c)
                    count++;

                    // If text[i] == cprime, we have found a
                    // opening bracket, so we return i if
                    // --count == 0
                else
                    if (x == cprime) {
                        if (--count == 0)
                            return i;
                    }
            }
        }
        else {
            // Count is 1 initially because we have already
            // `found' one opening bracket
            count = 1;

            // So we don't have to + 1 in every loop
            offset++;

            // Number of characters to check
            int len = doc.getLength () - offset;

            // Get text[offset+1,len];
            String text = doc.getText (offset, len);

            // Scan forwards
            for (int i = 0; i < len; i++) {
                // If text[i] == c, we have found another
                // opening bracket, therefore we will need
                // two closing brackets to complete the
                // match.
                char x = text.charAt (i);

                if (x == c)
                    count++;

                    // If text[i] == cprime, we have found an
                    // closing bracket, so we return i if
                    // --count == 0
                else
                    if (x == cprime) {
                        if (--count == 0)
                            return i + offset;
                    }
            }
        }

        // Nothing found
        return -1;
    }

    /**
     * Locates the start of the word at the specified position.
     *
     * @param line The text
     * @param pos  The position
     */
    public static int findWordStart (String line, int pos, String noWordSep) {
        char ch = line.charAt (pos - 1);

        if (noWordSep == null)
            noWordSep = "";
        boolean selectNoLetter = (!Character.isLetterOrDigit (ch)
                && noWordSep.indexOf (ch) == -1);

        int wordStart = 0;
        for (int i = pos - 1; i >= 0; i--) {
            ch = line.charAt (i);
            if (selectNoLetter ^ (!Character.isLetterOrDigit (ch) &&
                    noWordSep.indexOf (ch) == -1)) {
                wordStart = i + 1;
                break;
            }
        }

        return wordStart;
    }

    /**
     * Locates the end of the word at the specified position.
     *
     * @param line The text
     * @param pos  The position
     */
    public static int findWordEnd (String line, int pos, String noWordSep) {
        char ch = line.charAt (pos);

        if (noWordSep == null)
            noWordSep = "";
        boolean selectNoLetter = (!Character.isLetterOrDigit (ch)
                && noWordSep.indexOf (ch) == -1);

        int wordEnd = line.length ();
        for (int i = pos; i < line.length (); i++) {
            ch = line.charAt (i);
            if (selectNoLetter ^ (!Character.isLetterOrDigit (ch) &&
                    noWordSep.indexOf (ch) == -1)) {
                wordEnd = i;
                break;
            }
        }
        return wordEnd;
    }
}
